Nanotechnology offers small food for thought

Nanomaterials are already part of our diet and the vast majority are naturally occurring. But should 'artificial' nanoparticles be added to our foodstuffs?

Despite first being referred to nearly 40 years ago, the world of ‘nanotechnology’ – particularly in relation to food – is still a long way from being part of mainstream discussions. Photograph: Leandro Castelao

Imagine a humble grain of rice. Shrink it down a thousand times, and it becomes the size of a human skin cell. Shrink it a thousand times more, and you arrive at the nanoscale, where matter is measured in billionths of a metre.

Over the past three decades, scientists have developed a plethora of techniques that allow them to design and build structures at the nanoscale. Now they are applying these to our food.

Nanoparticles could smuggle vitamins into our daily diet, help deliver medicines where they are needed in the body, or even help to reduce food waste. "The possibilities seem endless," says Jeffrey Card, a toxicology expert at Intertek, a multinational safety consultancy that works extensively in the nanotech area. "Think of nanoscale filters to remove bacteria from milk and other beverages without boiling," he says, "or nanosensors to detect and alert consumers to pathogens or spoiled food."

"Some groups are even attempting 'molecular food manufacturing'," he adds. That involves creating food from its basic atomic components – carbon, hydrogen, oxygen, and so on – without the need for soil, seed or animals.

If "nanofood" sounds like science fiction, think again: nanomaterials are already on your plate. Natural processes used to make cheese, for example, produce nano-scale particles. But consumers tend to be more concerned by artificial nanoparticles that could be added to their food.

"The problem is that the qualities that make nanomaterials so attractive to researchers and industry across a wide range of fields, including food processing, are the same qualities that could make them harmful to human health," says Kathy Jo Wetter, who works on nanotechnology issues for the ETC Group, a campaigning organisation interested in technology's impact on health and the environment. For example, nanoparticles' small size can make some of them more "bioavailable", meaning that they are more likely to be absorbed by living tissue.

To date, only a handful of commercial food products contain artificial nanoparticles. The European Commission's Joint Research Centre says that two nanomaterials have been authorised for food applications in the European Union: a glazing agent called methacrylate copolymer, and titanium nitride nanoparticles that can help to make stronger plastic bottles. And in the US some iced doughnuts owe their alluring white sheen to nanoparticles of titanium dioxide, for example.

Food packaging

For now, nanotechnology is likely to have a bigger impact in food packaging. Nanoscale polymers are already used in some packaging to prevent oxygen leaking through, which extends a product's shelf life. Researchers have developed sensors based on nanoparticles that change colour in response to changing acidity levels or the presence of bacteria, which could indicate when food has spoiled. Eventually, such sensors could even trigger the release of preservatives when they detect food beginning to spoil.

Materials scientist Clara Silvestre, who works at the Institute of Chemistry and Technology of Polymers in Napoli, Italy, says that this sort of nanotechnology could play a key role in increasing sustainability, because roughly 30-40% of food is currently wasted.

Looking further into the future, "we could change the food itself or change the way the food is absorbed and operates through the system", says Norman Roy Scott, an emeritus professor of bioengineering at Cornell University in Ithaca, New York. Researchers are already learning how to encapsulate tiny droplets of one liquid inside another liquid, allowing them to be incorporated into food more easily, and then better absorbed by the body. Nano-capsules inside food could also be designed to release their contents over time, keeping you feeling full for longer.

David Julian McClements, a food scientist at the University of Massachusetts, says that oil-soluble vitamins, omega-3 and carotenoids (linked to eye health) are all candidates for encapsulation and incorporation into food. "These are all things that have very low solubility in water. Normally they have very low bioavailability," he says. "There is definitely potential for improving the bioavailability of these particles."

Some argue, however, that there is not enough long-term safety data on the nanoparticles that are already being used in packaging, which may end up being inadvertently eaten. And they are even more worried about deliberately incorporating nanoparticles into food – partly due to safety concerns, but also because it is yet another example of the control that large corporations exert over our food chain.

Ian Illuminato, Friends of the Earth's nanotechnology expert, says that there is already evidence that some nanoparticles can "get into organs they're not supposed to be in", such as the brain and the liver. "There are a lot of studies here that show red lights."

Illuminato says that while public concerns linked to new technologies and food have mainly focused on genetic modification, nanotechnology is gaining fast. "It's something that's going to be used more and more, and we're going to hear more and more about," he says.

Consumers are not the only group that could be affected. If nanomaterials do become prevalent in the food industry, more workers will become exposed to them for significant periods of time. Nanoparticles in packaging will also end up in waste, and may require specialist recycling.

At the moment, though, conclusive evidence of harm is thin on the ground. In 2011, Intertek reviewed the available studies on food-related nano-safety and concluded that there is "relatively little" published information available. "Much of the research that has been reported is substandard," says Card, "which makes it difficult to provide an overall conclusion on safety."

Many researchers agree with protestors who demand that any nanotech foods should be backed by substantial evidence of their long-term safety. "Like with all new technology there are benefits and potential risks," says McClements. "You have to make sure what you're doing is safe before you feed millions of people."

But they also point out that nanoparticles need to be assessed on a case-by-case basis. Something nano-sized is not automatically dangerous, says Mihail Roco, senior adviser for nanotechnology at the National Science Foundation in Washington DC, one of the US government's main research funding agencies.

On top of that, it's important to remember that natural nano-structures abound in our food already, he adds: "If you say nano-structures are dangerous, then you can't eat anything."

Agree or disagree with this article? Give us your views and help shape the debate on nanotechnology in the comments section below.